ASA 128th Meeting - Austin, Texas - 1994 Nov 28 .. Dec 02

1pSP9. Devoicing a /z/ does not make an /s/.

Div. of Head and Neck Surgery, UCLA School of Medicine, Los Angeles, CA
90024

It is well known that voiced stops in English tend not to be fully voiced.
For many American speakers, voiced fricatives may also have little or no
voicing. In what phonological contexts do speakers devoice underlying /z/?
Previous research [T. Veatch, Ling. Soc. Am. mtg., 69 (1989)] emphasized the
influence of the following segment. The present study confirms this, and
investigates the likelihood of devoicing in different positions in syllable,
word, and sentence. Five speakers of American English recorded multiple
repetitions of sentences in which /s/ and /z/ occurred in matched environments.
Measures of acoustic durations, airflow, and vocal fold vibration as evidenced
by EGG were used to compare the production of /z/ and /s/. Preliminary data
from one speaker show a variety of /z/'s, with the duration of vocal fold
vibrations as a percentage of fricative duration ranging from 0% to 100%.
However, the acoustic vowel length difference preceding /s/ and /z/ is
maintained, and even those tokens of /z/ in which there was no vocal fold
vibration have reduced airflow compared to matched tokens of /s/, suggesting
that devoiced /z/ may differ from underlying /s/ in glottal constriction or
level of pulmonic activity. [Work supported by NIH.]